The Angostura Formation is a Late Miocene (Mayoan to Montehermosan in the SALMA classification) geologic formation of the Borbón Basin in northwestern Ecuador.
Description The coarse sandstones and beds of conglomerates, about in thickness. The formation is resistant to erosion and is largely barren, but at a few places there are lenses or interbeds filled with finely preserved fossils. The formation overlies the Viche Formation, and is overlain by the lower Onzole Formation. The Angostura Formation is time-equivalent with the fossiliferous Gatún Formation of Panama.Angostura Formation at Fossilworks.org
Fossil content The formation has provided bivalve and gastropod fossils.
See also List of fossiliferous stratigraphic units in Ecuador
References
Further reading
P. Jung. 1989. Revision of the Strombina-group (Gastropoda; Columbellidae), fossil and living. Schweierische Paläontologische Abhandlungen 111:1-298 A. A. Olsson. 1964. Neogene Mollusks From Northwestern Ecuador E. H. Vokes and H. E. Vokes. 2000. Catalogue of Tulane University fossil localities.